It is about an "inter-community" tool or www template, which anyone can use as a central place to collect, display and link to everything that is meaningful for his "internet personality".
This would include things like his different nicknames in various communities, his reputation from auction sites, ..., and most importantly: his own contributions to the global community: articles, tutorials or other helpful texts, software, free content, etc. - everything that is helpful to a few or many others, but for which he doesn't charge a dime.

Communities could directly link to a member's "internet visiting card" (if that member wants to) instead of just that community's "about me" pages, and do a lot of other things, that are currently done in communities, but then on an global inter-community level (which people are trusting me, who's online, reputation, etc.).

I think, that someone, who is known for his history of contributing to the raising of other people's barns, should and will be helped more when he himself has a barn to raise.
But now it is that way: When someone goes from a community (where he was very helpful in the past) to another community on the internet, he is a stranger there and no one knows about his altruistic behavior in the former community.
He has to build his reputation from scratch again, which is especially bad when he doesn't have the skills that are necessary to help people in that new community. E. g. a programmer who helped a lot of people in software forums, who has now a complicated legal problem and goes to an apporpriate group. People there might give her more help, if they know that she gave a lot of help to other netizens for free in the past.

I guess other people already have thought about such a thing, or maybe it even exists?
What do you think about such a thing, and what do you see as a prerequisite for it to work?

Messages for Thomas:

Welcome, Thomas! I think that all your points are reasonable, the situation and the problem exists. GoByCar also talks about it. It is partially solved by people asking and telling about each other at a personal level, but a technical platform might solve that more conveniently. -- HelmutLeitner

Welcome. I would recommend just building a quick Wiki:SpikeSolution. You can then incorporate suggestions or comparable partial efforts into that as you hear them. Plus, it's a lot more interesting to have something tangible to play with. Go for it! -- SunirShah